Study On The Preparation Of The C4/C5/C6 Normal Paraffin Isomerization Catalysts

Current concerns on environmental pollution have led to imposition of some limitations on the amount of aromatics allowed in gasoline in many countries. Undoubtedly, given the high awareness in society of the environmental impact of gasoline products, these limitations are going to be more stringent in the future. These limitations have in turn led to increased research on the synthesis of branched paraffins, which are more environmentally friendly high-octane molecules. Current technologies for alkane isomerization employ catalysts containing H2SO4 or halides; however, their high toxicity, the difficulty in handling large amounts of such catalysts, and the environmental problems turned the industrial attention towards solid acid catalysts, which are safer and more environmentally friendly.The SO42-/ZrO2 solid-acid catalyst has many advantages, such as high acidity, not easy to corrode equipment and it has high catalytic activity for isomerization reaction. So it has extensive application prospect. This article mainly studied the best synthetic route of the SO42-/ZrO2 solid-acid catalyst, and also studied the effects on its structure and isomerization when different oxide was added. And we can get the following main conclusions:1、Akanes isomerization reaction is an exothermic reaction, lower temperature is good for the isomerization reaction, and when it’s up to a too high temperature, cracking reaction will be promoted. In this experiment, n-butane’s best reaction temperature is 230℃, and n-pentane and n-hexane is 250℃.2、The crystal form of ZrO2 has a great influence on the isomerization performance of the SO42-/ZrO2 catalyst.The ommitted step to influence the ZrO2 crystal form is the aging and roasting process. Taken together, when the aging time is 24h,the aging temperature is 15℃ and the calcination temperature is 600℃,the n-butane conversion is 4.75%, the i-butane selectivity is above 90%,the n-pentane conversion is 25.94%,the n-hexane conversion is 49.94%,the isomerization alkane selectivity is 80% approximately.3、The sulfur content on the SO42-/ZrO2 catalyst surface is also one of the important factors of its isomerization, the condition including the roasting temperature and the concentration of sulfuric acid when impregnating catalyst can both influence the sulfur content. When the sulfur content is lmol/L, the impregnation ratio is 10:1ml/g and the impregnation time is 4h, the isomerization performance of the SO42-/ZrO2 catalyst is optimal.4、SO42-/ZrO2 catalyst’s structure and isomerization performance were under the influence when the different oxides(such as Al2O3 TiO2、SiO2)were added in it, and the SZT catalyst in which 10% TiO2 was added can get the best n-butane isomerization performance of all.